A known plate heat exchanger includes a stack of substantially rectangular plates each having passage holes provided at four corners thereof, and passages in which water flows and passages in which a refrigerant flows that are formed between adjacent ones of the plates and alternately in a stacking direction, the passage holes functioning as inlets and outlets for the water and the refrigerant (see Patent Literature 1). In the plate heat exchanger, the water passages are closed near the passage holes that function as the inlet and the outlet for the refrigerant.